Such position measuring devices are employed for measuring the relative position of two components of a machine tool or a coordinate measuring machine.
A linear measuring device is known from German Patent Publication DE 25 05 587 C3, wherein the ends of a graduation support are suitably fastened to one of the components by hinge-like embodied fastening elements.
A similarly designed linear measuring device is described in European Patent Publication EP 0 110 059 B1. Elastic fastening means are provided on the ends and a rigid fastening element in the center of the housing. Fastening is done by means of a highly elastic adhesive layer in order to additionally prevent measuring inaccuracies in case of different coefficients Of expansion between the measurement representation and the support body.
In accordance with European Patent Publication EP 0 264 801 A1, the measurement representation is seated on spheres for linear compensation.
The linear measuring device in accordance with German Patent Publication DE 35 09 390 A1--on which the instant invention is based--has elastic fastening elements at the ends of the housing and further fastening elements located between them. These further fastening elements are fastening elbows which are clamped to the housing by means of sliding blocks engaging a groove. Elastic intermediate layers are intended to allow a translatory movement between the housing and the fastening elbows. However, it is disadvantageous that a tension-free connection cannot be made because of the screw fastening. It is impossible in actuality to tighten the screws with the sliding blocks evenly, so that different forces act on the housing at the individual fastening locations, which in turn can result in measurement errors.
In view of the above-review of the state of the art, it is an object of the present invention to provide a position measuring device wherein uneven thermal properties of the support body and the object to be measured and on which the support body is fastened cannot practically cause any falsification of the measured results.
It is another object of the present invention to provide a support body which is fastened relatively free of tension, yet which is stable.
Another object of the present invention is to provide simple and space-saving fastening.